It's like a chain of trust where everyone trusts the last person who shared something but you never know on who you are trusting at the start of this "chain" if you share. So people share a lot of BS :/
It's how literal 'fake news' has gotten into the mass media. Because a bunch of smaller sites fell for a fake news site quoting a (non existent) interview from anther site, and then the likes of the Metro and Daily Mail assumed they knew what they were talking about.
And that's not even getting into industries where copy and pasting stories is seen as a 'default'. The gaming press is very easy to 'compromise' with photoshopped pictures and fake information, since everyone basically just takes their news from everyone else.
So yeah, not a social media or average Joe exclusive issue here. But one which affects the media itself.
I know that myself, I have an implicit categorization in my head about which of my FB friends knows about what, and which friends are just prone to share random clickbait. I approach the news I see accordingly.